Encapsulation has been used in the food industry since the late 1960s, and normally involves coating a substrate or ingredient before introducing it into a food system. The combination of the coating and the ingredient is referred to as an encapsulate. Food ingredients are encapsulated for a variety of reasons, including protection of the ingredient from degradation during processing and storage, timed release of the ingredient, prevention of premature reactions, prevention of unwanted reactions catalyzed by minerals, emulsification, precise delivery of the ingredient in the food system, taste masking of vitamins and minerals, and suspension of ingredients. As a particular example, the encapsulation of salt in yeast-leavened baked goods protects the yeast from any harmful effects of the salt. As another example, encapsulating acidulants prevents the unwanted acid hydrolysis of other ingredients. Ingredients which have commonly been encapsulated include amino acids, ascorbic acid, calcium lactate, citric acid, sorbic acid, potassium sorbate, hydrocolloids, iron, lactic acid and sodium chloride. These and other encapsulated ingredients are used in a variety of food systems such as sausages, meat snacks, seasoning blends, dessert mixes, dry beverage and bakery mixes, microwaveable products and nutritional and functional food systems. Additionally, encapsulation has been used to protect biologically active materials, such as enzymes and microorganisms, against harmful substances like moisture and oxygen, and thus prolong the storage stability of these biologically active materials. The encapsulating material or coating is typically composed of a lipid or lipid mixture such as a hydrogenated vegetable oil and/or mono and diglycerides, waxes, or water soluble hydrocolloids such as gums or maltodextrins. More recently, the development of larger molecules such as cyclodextrins, which form complexes around and thereby encapsulate particles, have been used.
To accomplish the intended purposes of encapsulation, an encapsulate is designed so that its coating protects the ingredient, and thereafter at some time during the food processing cycle disintegrates and releases the ingredient into the food system. In general, the release of the substrate or ingredient from the encapsulate depends upon the melting point of the coating, the water and fat solubility of the coating, and the emulsification of the system. For lipid coatings, heat is normally used to dissolve the coating and release the encapsulated ingredient into the food system. For hydrocolloid coatings, the presence of moisture in the food system is normally the agent causing the disintegration.
An example of a fat used for a lipid coating is hydrogenated soybean oil. Fully hydrogenated soybean oil has a melting point of approximately 158.degree. F., and an encapsulate using it would release its ingredient when the food system approaches or attains that temperature. The lipid chosen for the coating depends of course on the food system in which it will be used. The particular coating may be chosen not only based upon the temperature profile of a food process, but to allow a scientist to dictate the temperature profile of the process. For example, the scientist may choose a lipid coating which is less saturated so that high temperatures are not used solely to cause the release of an ingredient from the encapsulate. This strategy is particularly important in sausage making as will be described in detail infra. On the contrary, vitamin and mineral enrichments in baking dough would probably be coated with a high melting point fat (158.degree. F.) so that they are protected from reaction with dough components during fermentation and most of the baking cycle, but thereafter are released in the last stages of baking so that they are available for absorption when the product is consumed. While waxes are sometimes used, for example when oxidative stability is a factor, hydrogenated oils are by far the most widely used lipid coatings.
On the other hand, hydrocolloids, such as gums, maltodextrins and modified starches are used when a predominantly water-soluble coating is desired. The ingredient is released primarily by the breakdown of the coating through its exposure to moisture in the food system, although elevated temperatures also contribute to the breakdown of such a coating. The rate of ingredient release can be controlled by the ratio of coating to ingredient. A thicker coating takes longer to dissolve, thereby releasing the ingredient later in the processing cycle.
While encapsulation has been used in the food industry for almost 30 years, prior art systems of ingredient encapsulation, while effective, have some shortcomings when the so-called "low-melt" coatings are used. First, prior art encapsulated ingredients have poor flowability characteristics, and also have a tendency to cake up and dough up. Additionally, prior art encapsulations do not exhibit a very tight seal, i.e. ingredients leach out of the encapsulate prematurely. In general, prior art coatings have broad melting ranges and higher melting points, making it difficult to deliver the proper amount of ingredient at the correct time. Specifically, a food system may not attain the conditions for the disintegration of the coating, or the conditions for breakdown may be reached at an incorrect time (either too early or too late), and the ingredient will either be released at a time where it cannot function properly or worse yet, where it has a pernicious effect on the food system. There is also the possibility that the conditions for the disintegration of the coating are not attained and the ingredient is never released into the food system. This latter possibility may be a particular problem in the processing of low temperature meats, such as winter sausages, where acid is encapsulated for later release into the meat, but where the processing temperatures never reach levels which cause the disintegration of the coating, and the ingredients are therefore never released into the meat product. If the coating does not disintegrate in the manufacture of winter sausage, the pH is not lowered and proper preservation and stabilization of the sausage is never obtained.
This slow release of acid from encapsulates allows the salt in the meat emulsion to work, i.e. to extract the salt soluble proteins and form a protein matrix, and prevents premature denaturing of the protein by a sudden drop of the pH if acid is added directly without encapsulation or a high-leach encapsulated acid is used. This matrix binds the meat particles, spices and other ingredients thereby forming the sausage prior to the acidification. The entire matrix is then denatured by the subsequent acid release from the disintegration of the encapsulate, resulting in a coagulation and precipitation of the protein structure. If the protein is denatured too rapidly, matrix formation is prevented by the precipitation of individual protein particles not initially bound into a matrix. This results in a soft mushy texture with minimal integrity.
In the production of sausage, some attempts have been made to use lower melting point oils obtained by fractionation or partial hydrogenation for the coating such as high oleic canola stearine (Cargill) and Astral R (AC Humko). However, fractionated stearines possess soft and sticky physical characteristics which do not make them suitable for encapsulation. The use of such oils therefore has been met with limited success since the oils' broad melting range and high degree of unsaturation results in poor flowability and protection of the ingredients, caking, and leaky encapsulations. Consequently, an improved encapsulate and process are needed in the food industry for low temperature processes.
A low-melt encapsulation would also be advantageous when encapsulating materials with biological activity, such as enzymes and microorganisms that are highly sensitive to temperature and moisture. It is well known among those skilled in the art that enzymes and microorganisms can be inactivated when exposed to elevated temperature (e.g. &gt;40.degree. C. or 104.degree. F.), especially in combination with exposure to moisture. While encapsulation has been considered as a means to provide additional protection to these biologically active materials and thus prolong their shelflife or storage stability, certain difficulties arise with more conventional encapsulation processes and coatings as most prior art processes and coatings require a much higher temperature during the encapsulation process than tolerable by the biologically active materials.
Consequently, it is an object of the present invention to improve the quality, characterisitics, effectiveness and precision of encapsulates in the food industry.
It is another object of the present invention to develop an encapsulate that can be effectively used in low temperature food processing environs.
It is a further object of the present invention to develop such an encapsulate using a low melting point fat which is hard and dry and room temperature, and melts in a sharp and narrow range at slightly higher than room temperature.
It is a further object of the invention to develop an encapsulate which is more tightly formed than prior art encapsulates, thereby preventing premature leakage of the encapsulated material.
It is a still further object of the present invention to use a low-melt encapsulated acid in the production of low temperature meats such as winter sausage.
It is another object of the present invention to use a low melting point fat to encapsulate biologically active substrates.
The present invention accomplishes these and other objectives.